Hitherto, it has only been possible to produce a metal structure in foam form, also known as a metal foam, with considerable technical difficulty and high levels of financial outlay.
One known production process consists in foaming aluminum to approx. 1.5 times its original volume. The metal structure in foam form which is thereby formed is a closed-pore structure, i.e. having a large number of pores per unit volume. This aluminum metal structure in foam form is extraordinarily expensive to produce and even this production operation is questionable in ecological terms.
Another known process consists in evaporation-coating a nonconductive plastic substrate which has a foamed structure, i.e. a structure with pores, with metal. In this case, the plastic substrate has to be in panel form and must not exceed a thickness of 1–2 mm. The evaporation coating takes place from the two opposite main sides of the substrate. Only this small thickness can ensure that the surface of the plastic substrate can be provided with a metal layer even in inner regions. After the evaporation coating, the plastic substrate which has been pretreated in this way is introduced into an electroplating device, so that the thin metal layer on the surface of the foamed substrate is thickened by electroplating. On account of the extremely high production costs, the metal structure in foam form which is produced in this manner is not currently in widespread industrial use on account of its high costs. A particular drawback is that the thickness and shape (panel shape) of the plastic substrate are limited by the production technology.